1. Field of the Invention
The present invention relates to a method and apparatus for making an inner packaging container, having anti-electrostatic characteristics, from an aqueous slurry of pulp dispersed with carbon fibers by use of a mold adapted to be immersed in the pulp slurry and a suction means. In particular, the present invention relates to a method and apparatus for making an inner packaging container, in which fiber components of a pulp slurry, which is prepared by dissolving or dispersing pulp and carbon fibers in water together with sizing agents and additives, are deposited over a mold surface of a lower mold perforated with a number of pores and defined with a suction chamber, under the condition in which a reduction of pressure occurs in the suction chamber, and molded into a desired shape by the lower mold along with an upper mold engaging with the lower mold, and then subjected to dewatering, separating and drying processes, thereby forming an anti-electrostatic packaging container having an integral structure.
2. Description of the Prior Art
In regard to inner packaging materials for packaging an article having a specific shape, packaging containers have been known which are made of planar white boards, hard boards, or corrugated sheets. Such packaging containers are made by cutting a board or sheet into a desired shape, and then folding or bending the cut board or sheet into a shape desired to be in tight contact with an article to be packaged. However, it is difficult for such packaging containers to have a shape conforming to the shape of an article to be packaged because the manufacture of such packaging containers involves many processes such as cutting, folding, bending, and bonding processes. As a result, it is impossible to expect a precise packaging.
In order to solve such a problem, inner packaging containers made of synthetic resin foam have been proposed. Although such packaging containers provide a stable and precise packaging, they involve a problem in regard to environmental pollution. Furthermore, it is impossible to expect, from such packaging containers, an anti-electrostatic effect which is desired in accordance with the present invention.
Recently developed electronic elements and electronic appliances, which consist of highly dense integrated circuits, may be damaged by even weak static electricity. As a result, expensive electronic products may be out of order or operate abnormally. The generation of static electricity may also involve a danger of an accident such as burning of inflammables having a low fire point or an explosion of explosive materials, for example, gunpowder.
In order to eliminate such problems, aluminum foils have been proposed which are used to package products by units. Also, anti-electrostatic packaging materials have been proposed which are coated with a coating consisting of carbon powder mixed with an appropriate paint.
However, packaging materials such as aluminum foils are expensive in regard to the costs of the material used and the costs of labor. Aluminum foils may cause damage to packaged articles due to a high hardness thereof. On the other hand, anti-electrostatic packaging materials coated with a coating may dissolve parts of electronic elements or electronic appliances made of synthetic resin because the coating contains an organic solvent, drying oil or semi-drying oil. As a result, the packaged articles may be damaged. Furthermore, the packaged articles may be contaminated with the coating. Bad odor may also be generated from such packaging materials.
Recently, a conductive packaging sheet has also been proposed which is disclosed in Korean Patent Publication No. 92-169.
This conductive packaging sheet is made of pulp and carbon fibers in accordance with a papermaking process. Such a conductive packaging sheet may be used to directly wrap an electronic element or electronic appliance. Otherwise, it is used in the form of an inner packaging container having a certain shape after being bonded to a white board, hard board or corrugated board, and then subjected to cutting, folding and bending processes.
Although such a packaging container is conductive, it exhibits a degraded packaging tightness. For this reason, it is impossible to expect a precise packaging using such a packaging container. This packaging container cannot be regarded to be a high-grade packaging container.
Therefore, an object of the invention is to provide a method and apparatus for making a packaging material exhibiting a conductivity while having a high quality so as to enhance the performance and competitiveness, taking into consideration the current global tendency to avoid the use of packaging containers made of synthetic resin materials resulting in environmental pollution.
In accordance with one aspect, the present invention provides an apparatus for making an anti-electrostatic packaging container comprising: a pulp slurry making tank; a molding tank for receiving a pulp slurry supplied from the pulp slurry making tank via a pipe; a hydraulic device arranged beneath the molding tank, the hydraulic device having a vertically reciprocating piston extending vertically through a bottom wall of the molding tank into the interior of the molding tank; a lower mold arranged in the interior of the molding tank and mounted at a bottom wall thereof to an upper end of the piston in such a fashion that it moves vertically in the molding tank in accordance with a reciprocal movement of the piston, the lower mold having a top wall perforated with a number of pores and adapted as a lower surface of a mold cavity; the suction chamber defined in the lower mold beneath the top wall of the lower mold and connected to a motor installed outside the molding tank via a flexible hose extending from the motor to the interior of the molding tank, the suction chamber communicating with the interior of the molding chamber via the pores perforated through the top wall of the lower mold; an upper mold arranged in a fixed state near a top wall of the molding tank in the interior of the molding tank in such a fashion that it is vertically aligned with the lower mold, the upper mold engaging with the lower mold at edges thereof to define said mold cavity therebetween and having a bottom wall perforated with a number of pores and adapted as an upper surface of the mold cavity; and an air sucking and blowing chamber defined in the upper mold and connected to a reversible motor installed outside the molding tank via an air pipe extending from the reversible motor to the upper mold, the air sucking and blowing chamber communicating with the mold cavity via the pores perforated through the bottom wall of the upper mold.
In accordance with another aspect, the present invention provides a method for making an anti-electrostatic packaging container using the above mentioned packaging container making apparatus according to the present invention, comprising the steps of: dispersing beaten sulfite pulp and carbon fibers in water, adding, to the resulting aqueous solution, rosin and aluminum sulfate as sizing agents, sparsely acetificated PVA fibers and a melamine resin or urea resin as additives, and a starch material, and sufficiently stirring the resulting mixture in the pulp slurry making tank, thereby producing a pulp slurry; supplying the pulp slurry from the pulp slurry making tank to the molding tank until the lower mold is completely immersed in the supplied pulp slurry in the molding tank; generating a suction force in the suction chamber by an operation of the motor, thereby depositing fiber components of the pulp slurry to a desired thickness over the top wall of the lower mold; stopping the operation of the motor, and then upwardly moving the lower mold by an operation of the hydraulic device until the lower mold comes into contact with the upper mold, thereby molding said deposited fiber components of the pulp slurry into a packaging container while dewatering the molded packaging container; generating a suction force in the air sucking and blowing chamber by a normal operation of the reversible motor while downwardly moving the lower mold, thereby separating the molded packaging container from the lower mold; blowing air into the air sucking and blowing chamber by a reverse operation of the reversible motor, thereby separating the molded packaging container from the upper mold; and drying and curing the molded packaging container for 10 to 20 minutes while passing said molded packaging container through a drying tunnel maintained at a temperature of 50 to 120xc2x0 C.